EMC is using Microsoft research into flash use as a memory tier between DRAM and disk drives to speed up Data Domain deduplication.
FlashStore is a Microsoft research project that batches up flash writes in a server's main memory and then writes them as a page or block, in effect turning random flash writes into sequential ones …

NetApp’s Data ONTAP does something uniquely different from the majority of other storage vendors’ products; it’s optimized for writes. Indeed, write optimization was one of the original design criteria for Data ONTAP back in 1992. Dave Hitz himself explained this many years ago in TR-3001 (since updated). In brief, Data ONTAP eliminates the “Disk Parity Bottleneck” through its use of WAFL to coalesce a group of temporally located write IOs; pre-emptively “defrag” if you will this group of I/Os based upon the best possible allocation unit or “tetris” available; calculate parity for the entire lot while in memory, and stripe the lot of them across all available drives during the next write event (aka consistency point, CP).

"Data ONTAP eliminates the “Disk Parity Bottleneck” through its use of WAFL to coalesce a group of temporally located write IOs" -- That part is done via a write cache battery-backed DIMM(s)...